1. Field of the Invention
The present invention relates generally to a snubber employable for a paper feeding unit such as a paper feeding cassette or the like to constitute a paper disjointing mechanism. More particularly, the present invention relates to a paper disjointing device for a paper feeding unit such as a paper feeding cassette or the like which is constructed such that a snubber on the movable side arranged for a movable side guide can generate a depressing force having the same value as that of a snubber on the stationary side.
2. Description of the Related Art
An electronic copying unit, a paper feeding cassette, or a similar unit is equipped with paper receiving means such as a paper feeding tray, a paper feeding cassette, or the like in a paper feeding section so as to deliver paper by actuating paper feeding means. The feeding means includes such elements as a paper feeding roller or the like arranged for the paper receiving means. Among the foregoing type of paper receiving means, a paper feeding tray or the like having a capability of receiving a number of papers is equipped merely with a mechanism for upwardly squeezing each paper toward the paper feeding roller. Paper disjointing means is arranged downstream of the paper feeding roller as disclosed in, e.g., an official gazette of Japanese Unexamined Patent Publication (KoKai) No. 62-175330. As a paper is delivered from the paper feeding tray by rotating the paper feeding roller, it is disjointed from a paper located below the first-mentioned paper with the aid of a paper disjointing mechanism so as to allow paper to be delivered to an image transferring section one by one.
In contrast with the aforementioned paper receiving means, another paper receiving means such as a paper feeding cassette or the like having a capability of receiving a comparatively small number of papers is constructed such that snubbers are arranged at corners on the opposite sides as seen in the paper delivering direction for papers received in the paper feeding tray so as to allow each snubber to perform a paper disjointing operation for the respective papers. A paper feeding cassette constructed as disclosed in, e.g., an official gazette of Japanese Unexamined Utility Model Publication (KoKai) No. 58-131234 can be noted as a paper feeding cassette of the last-mentioned type. With respect to the conventional paper feeding cassette including snubbers on the opposite side as seen in the paper delivering direction, a snubber on the reference line side is arranged at a stationary position, and the other snubber is arranged on a side guide. The snubber arranged on the side guide is displaced corresponding to a size of each paper to be used so that corner portions of the snubber on the opposite sides as seen in the paper discharging direction are held in the engaged state together with the snubber on the stationary side.
With respect to the paper feeding cassette constructed in the above-described manner, a paper feeding roller is arranged at the substantially central part of the foremost end of the paper feeding cassette as seen in the paper delivering direction so as to constitute a paper feeding section. As each paper is fed by rotating the paper feeding roller, it is gradually bent, and thereafter, the snubbers serving to depress corners of the paper on the opposite sides are slightly raised up attributable to the toughness of the paper itself. Subsequently, since only the uppermost paper passes past the snubber, a paper feeding operation is performed for each paper to be delivered from the paper feeding cassette while receiving disjointing resistance caused by the snubbers.
In many cases, the snubber arranged for the side guide in the paper feeding cassette is displaced with the aid of a guide cutout formed on the bottom plate of the paper feeding cassette until it is immovably kept at the position corresponding to the side edge of each paper. Because the snubber on the movable side is constructed in such a configuration as not to obstruct any turning movement of the bottom plate of the paper feeding cassette, there arises a necessity for forming a cutout which makes it possible for a part of the bottom plate to turn. Because of the foregoing necessity, the snubber on the movable side unavoidably constructed in such a state that a part of a plate constituting the snubber on the stationary side is cut out therefrom. For this reason, there arises a malfunction that both the snubbers are different from each other in weight.
In addition, in case that two snubbers for imparting a depressing function to corners of each paper on the opposite side as seen in the paper delivering direction exhibit a depressing power different from each other, there arises a problem that each paper is readily slantwise delivered from the paper feeding cassette. In other words, in case that a depressing power generated by each of the snubbers is different from each other, as a paper is delivered by the paper feeding roller, one of the corners of the paper depressed by the snubber having a light weight passes past the snubber ahead of the other corner, and thereafter, the other corner of the paper passes past the snubber having a heavy weight with delay. When papers are successively delivered from the paper feeding unit in the slantwise feeding state as mentioned above, an image fails to be built on each paper at a correct position. Thus, there arises another malfunction that all images are erroneously transferred to each paper, resulting in more work for an operator. Once a paper is slantwise delivered, a corner of the paper is engaged with another certain member in a paper transference passage extending from the paper feeding unit such as a paper feeding cassette or the like to the image transferring section, causing a paper feeding operation to be incorrectly performed. This results in increasing the workload of the operator because he must clear the paper transference passage that is jammed with the delivered paper.